The present invention relates to an anchor bolt to be anchored by an explosive charge in a blind bore in a solid material, in particular a rock face or concrete, wherein the anchor bolt has a deformation chamber containing the explosive charge.
Anchor bolts of the above mentioned general type are known in the art. One of such anchor bolts is disclosed for example in the German document DE-OS 36 13 624. The anchor bolt disclosed here has a deformation chamber which is completely filled with an explosive capsule. Ignition of the explosive capsule is effected by way of a triggering tool which is applied through an internal bore of the anchor bolt against the end wall of the explosive capsule. Because of this triggering mechanism only sleeve-like anchor bolts can be anchored. Moreover, to build up the pressure of the explosion for the purpose of deforming and forcing the outer surface of the anchor bolt outward, an additional capsule for the explosive charge which absorbs the pressure of the explosion is required. Since the deformation chamber of the anchor bolt is expanded by the outward bulging of the capsule, the size of the deformation chamber determines the amount of explosive and the size of the capsule. This dependency means that a relatively large explosive capsule filled with explosive is required to fill the deformation chamber completely. But the potential danger factors are increased thereby.
An anchor bolt anchorable in a rock face by means of an explosive charge is also known from U.S. Pat. No. 2,573,880. In this solution, a ram located inside the bolt is driven by means of an explosive charge to the leading end of the bolt, whereupon expansion and thus fixing of the bolt is effected. Ignition of the charge is effected by means of an electric ignition device which is in direct contact with the explosive charge. The ignition line is lead outward on the outside of the bolt. The ignition line may therefore suffer damage or even be torn off during placement of the anchor bolt.